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authorAndrey Andreev <narf@devilix.net>2018-06-12 15:45:46 +0200
committerAndrey Andreev <narf@devilix.net>2018-06-12 15:45:46 +0200
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tree391bc1e62d8d0ad045e18a6da72e3e2a59e91503 /user_guide_src/source/general/controllers.rst
parenta9da3dd2f16a8f97d7bc4ff5572b28e4bb84c813 (diff)
[ci skip] 3.1.9 release
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-###########
-Controllers
-###########
-
-Controllers are the heart of your application, as they determine how
-HTTP requests should be handled.
-
-.. contents:: Page Contents
-
-What is a Controller?
-=====================
-
-**A Controller is simply a class file that is named in a way that can be
-associated with a URI.**
-
-Consider this URI::
-
- example.com/index.php/blog/
-
-In the above example, CodeIgniter would attempt to find a controller
-named Blog.php and load it.
-
-**When a controller's name matches the first segment of a URI, it will
-be loaded.**
-
-Let's try it: Hello World!
-==========================
-
-Let's create a simple controller so you can see it in action. Using your
-text editor, create a file called Blog.php, and put the following code
-in it::
-
- <?php
- class Blog extends CI_Controller {
-
- public function index()
- {
- echo 'Hello World!';
- }
- }
-
-Then save the file to your *application/controllers/* directory.
-
-.. important:: The file must be called 'Blog.php', with a capital 'B'.
-
-Now visit the your site using a URL similar to this::
-
- example.com/index.php/blog/
-
-If you did it right, you should see:
-
- Hello World!
-
-.. important:: Class names must start with an uppercase letter.
-
-This is valid::
-
- <?php
- class Blog extends CI_Controller {
-
- }
-
-This is **not** valid::
-
- <?php
- class blog extends CI_Controller {
-
- }
-
-Also, always make sure your controller extends the parent controller
-class so that it can inherit all its methods.
-
-Methods
-=======
-
-In the above example the method name is ``index()``. The "index" method
-is always loaded by default if the **second segment** of the URI is
-empty. Another way to show your "Hello World" message would be this::
-
- example.com/index.php/blog/index/
-
-**The second segment of the URI determines which method in the
-controller gets called.**
-
-Let's try it. Add a new method to your controller::
-
- <?php
- class Blog extends CI_Controller {
-
- public function index()
- {
- echo 'Hello World!';
- }
-
- public function comments()
- {
- echo 'Look at this!';
- }
- }
-
-Now load the following URL to see the comment method::
-
- example.com/index.php/blog/comments/
-
-You should see your new message.
-
-Passing URI Segments to your methods
-====================================
-
-If your URI contains more than two segments they will be passed to your
-method as parameters.
-
-For example, let's say you have a URI like this::
-
- example.com/index.php/products/shoes/sandals/123
-
-Your method will be passed URI segments 3 and 4 ("sandals" and "123")::
-
- <?php
- class Products extends CI_Controller {
-
- public function shoes($sandals, $id)
- {
- echo $sandals;
- echo $id;
- }
- }
-
-.. important:: If you are using the :doc:`URI Routing <routing>`
- feature, the segments passed to your method will be the re-routed
- ones.
-
-Defining a Default Controller
-=============================
-
-CodeIgniter can be told to load a default controller when a URI is not
-present, as will be the case when only your site root URL is requested.
-To specify a default controller, open your **application/config/routes.php**
-file and set this variable::
-
- $route['default_controller'] = 'blog';
-
-Where 'blog' is the name of the controller class you want used. If you now
-load your main index.php file without specifying any URI segments you'll
-see your "Hello World" message by default.
-
-For more information, please refer to the "Reserved Routes" section of the
-:doc:`URI Routing <routing>` documentation.
-
-Remapping Method Calls
-======================
-
-As noted above, the second segment of the URI typically determines which
-method in the controller gets called. CodeIgniter permits you to override
-this behavior through the use of the ``_remap()`` method::
-
- public function _remap()
- {
- // Some code here...
- }
-
-.. important:: If your controller contains a method named _remap(),
- it will **always** get called regardless of what your URI contains. It
- overrides the normal behavior in which the URI determines which method
- is called, allowing you to define your own method routing rules.
-
-The overridden method call (typically the second segment of the URI) will
-be passed as a parameter to the ``_remap()`` method::
-
- public function _remap($method)
- {
- if ($method === 'some_method')
- {
- $this->$method();
- }
- else
- {
- $this->default_method();
- }
- }
-
-Any extra segments after the method name are passed into ``_remap()`` as an
-optional second parameter. This array can be used in combination with
-PHP's `call_user_func_array() <http://php.net/call_user_func_array>`_
-to emulate CodeIgniter's default behavior.
-
-Example::
-
- public function _remap($method, $params = array())
- {
- $method = 'process_'.$method;
- if (method_exists($this, $method))
- {
- return call_user_func_array(array($this, $method), $params);
- }
- show_404();
- }
-
-Processing Output
-=================
-
-CodeIgniter has an output class that takes care of sending your final
-rendered data to the web browser automatically. More information on this
-can be found in the :doc:`Views <views>` and :doc:`Output Class
-<../libraries/output>` pages. In some cases, however, you might want to
-post-process the finalized data in some way and send it to the browser
-yourself. CodeIgniter permits you to add a method named ``_output()``
-to your controller that will receive the finalized output data.
-
-.. important:: If your controller contains a method named ``_output()``,
- it will **always** be called by the output class instead of
- echoing the finalized data directly. The first parameter of the
- method will contain the finalized output.
-
-Here is an example::
-
- public function _output($output)
- {
- echo $output;
- }
-
-.. note::
-
- Please note that your ``_output()`` method will receive the
- data in its finalized state. Benchmark and memory usage data
- will be rendered, cache files written (if you have caching
- enabled), and headers will be sent (if you use that
- :doc:`feature <../libraries/output>`) before it is handed off
- to the ``_output()`` method.
- To have your controller's output cached properly, its
- ``_output()`` method can use::
-
- if ($this->output->cache_expiration > 0)
- {
- $this->output->_write_cache($output);
- }
-
- If you are using this feature the page execution timer and
- memory usage stats might not be perfectly accurate since they
- will not take into account any further processing you do.
- For an alternate way to control output *before* any of the
- final processing is done, please see the available methods
- in the :doc:`Output Library <../libraries/output>`.
-
-Private methods
-===============
-
-In some cases you may want certain methods hidden from public access.
-In order to achieve this, simply declare the method as being private
-or protected and it will not be served via a URL request. For example,
-if you were to have a method like this::
-
- private function _utility()
- {
- // some code
- }
-
-Trying to access it via the URL, like this, will not work::
-
- example.com/index.php/blog/_utility/
-
-.. note:: Prefixing method names with an underscore will also prevent
- them from being called. This is a legacy feature that is left
- for backwards-compatibility.
-
-Organizing Your Controllers into Sub-directories
-================================================
-
-If you are building a large application you might want to hierarchically
-organize or structure your controllers into sub-directories. CodeIgniter
-permits you to do this.
-
-Simply create sub-directories under the main *application/controllers/*
-one and place your controller classes within them.
-
-.. note:: When using this feature the first segment of your URI must
- specify the folder. For example, let's say you have a controller located
- here::
-
- application/controllers/products/Shoes.php
-
- To call the above controller your URI will look something like this::
-
- example.com/index.php/products/shoes/show/123
-
-Each of your sub-directories may contain a default controller which will be
-called if the URL contains *only* the sub-directory. Simply put a controller
-in there that matches the name of your 'default_controller' as specified in
-your *application/config/routes.php* file.
-
-CodeIgniter also permits you to remap your URIs using its :doc:`URI
-Routing <routing>` feature.
-
-Class Constructors
-==================
-
-If you intend to use a constructor in any of your Controllers, you
-**MUST** place the following line of code in it::
-
- parent::__construct();
-
-The reason this line is necessary is because your local constructor will
-be overriding the one in the parent controller class so we need to
-manually call it.
-
-Example::
-
- <?php
- class Blog extends CI_Controller {
-
- public function __construct()
- {
- parent::__construct();
- // Your own constructor code
- }
- }
-
-Constructors are useful if you need to set some default values, or run a
-default process when your class is instantiated. Constructors can't
-return a value, but they can do some default work.
-
-Reserved method names
-=====================
-
-Since your controller classes will extend the main application
-controller you must be careful not to name your methods identically to
-the ones used by that class, otherwise your local functions will
-override them. See :doc:`Reserved Names <reserved_names>` for a full
-list.
-
-.. important:: You should also never have a method named identically
- to its class name. If you do, and there is no ``__construct()``
- method in the same class, then your e.g. ``Index::index()``
- method will be executed as a class constructor! This is a PHP4
- backwards-compatibility feature.
-
-That's it!
-==========
-
-That, in a nutshell, is all there is to know about controllers.